Anyone got ideas? or GMs must be employees of PA?

You have to be employed and this has nothing to do with gameplay. Use the off-topic section next time.

Yes they are employees of PA, so like any other job, send resumes when they're looking for one, get interview 
Being a GM is not just having a cool costume in game and done, it's a real job with a ton of responsability and work

You're lucky, there are looking for one, so if you have the qualification, here is your chance https://apply.workable.com/pearlabyss/j/C646A61954/

I'd also be interested in being a GM in Black Desert. I've been playing for 6 years and spend a lot of time gaming. I've helped countless adventurers, as well as have been blessed to know many good people that have also helped me! I gravitate toward people in Black Desert that need information or help, as I realized we all learn on our own time. I view most gamers as introverts that just need a little inspiration to make great things happen in their community and/or just for themselves. If anyone hears of a job opening contact me either via In-game - Koga_Nagihasanni or by following me on twitch and communicating it to me that way! KogaNagiTTV

Job listings are posted here: https://pearl-abyss-america.breezy.hr/ (NA) or https://apply.workable.com/pearlabyss-europe/#jobs (EU)